[RFC] [PATCH 2/2] perf/probe: Detect probe target when m/x options are absent

[Srikar Dronamraju]

From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

Options -m and -x explicitly allow tracing of modules / user space
binaries. In absense of these options, check if the first argument
can be used as a target.

perf probe /bin/zsh zfree is equivalent to perf probe -x /bin/zsh
zfree.

Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
 tools/perf/Documentation/perf-probe.txt |    8 ++++--
 tools/perf/builtin-probe.c              |   43 +++++++++++++++++++++++++++++--
 2 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index fb673be..51205f0 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -104,6 +104,10 @@ OPTIONS
 	Specify path to the executable or shared library file for user
 	space tracing. Can also be used with --funcs option.
 
+In absence of -m/-x options, perf probe checks if the first argument after
+the options is an absolute path name. If its an absolute path, perf probe
+uses it as a target module/target user space binary to probe.
+
 PROBE SYNTAX
 ------------
 Probe points are defined by following syntax.
@@ -190,11 +194,11 @@ Delete all probes on schedule().
 
 Add probes at zfree() function on /bin/zsh
 
- ./perf probe -x /bin/zsh zfree
+ ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
 
 Add probes at malloc() function on libc
 
- ./perf probe -x /lib/libc.so.6 malloc
+ ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
 
 SEE ALSO
 --------
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index ee3d84a..e215ae6 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -85,21 +85,58 @@ static int parse_probe_event(const char *str)
 	return ret;
 }
 
+static int set_target(const char *ptr)
+{
+	int found = 0;
+	const char *buf;
+
+	/*
+	 * The first argument after options can be an absolute path
+	 * to an executable / library or kernel module.
+	 *
+	 * TODO: Support relative path, and $PATH, $LD_LIBRARY_PATH,
+	 * short module name.
+	 */
+	if (!params.target && ptr && *ptr == '/') {
+		params.target = ptr;
+		found = 1;
+		buf = ptr + (strlen(ptr) - 3);
+
+		if (strcmp(buf, ".ko"))
+			params.uprobes = true;
+
+	}
+
+	return found;
+}
+
 static int parse_probe_event_argv(int argc, const char **argv)
 {
-	int i, len, ret;
+	int i, len, ret, found_target;
 	char *buf;
 
+	found_target = set_target(argv[0]);
+	if (found_target && argc == 1)
+		return 0;
+
 	/* Bind up rest arguments */
 	len = 0;
-	for (i = 0; i < argc; i++)
+	for (i = 0; i < argc; i++) {
+		if (i == 0 && found_target)
+			continue;
+
 		len += strlen(argv[i]) + 1;
+	}
 	buf = zalloc(len + 1);
 	if (buf == NULL)
 		return -ENOMEM;
 	len = 0;
-	for (i = 0; i < argc; i++)
+	for (i = 0; i < argc; i++) {
+		if (i == 0 && found_target)
+			continue;
+
 		len += sprintf(&buf[len], "%s ", argv[i]);
+	}
 	params.mod_events = true;
 	ret = parse_probe_event(buf);
 	free(buf);


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